Bluetooth: hci_uart: Add new line discipline enhancements

Added the ability to flow control the UART, improved the UART baud
rate setting, transferred the speeds into line discipline from the
protocol and introduced the tty init function.
Signed-off-by: Ilya Faenson <ifaenson@broadcom.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_ldisc.c

@@ -266,6 +266,85 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
 	return 0;
 }
 
+/* Flow control or un-flow control the device */
+void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
+{
+	struct tty_struct *tty = hu->tty;
+	struct ktermios ktermios;
+	int status;
+	unsigned int set = 0;
+	unsigned int clear = 0;
+
+	if (enable) {
+		/* Disable hardware flow control */
+		ktermios = tty->termios;
+		ktermios.c_cflag &= ~CRTSCTS;
+		status = tty_set_termios(tty, &ktermios);
+		BT_DBG("Disabling hardware flow control: %s",
+		       status ? "failed" : "success");
+
+		/* Clear RTS to prevent the device from sending */
+		/* Most UARTs need OUT2 to enable interrupts */
+		status = tty->driver->ops->tiocmget(tty);
+		BT_DBG("Current tiocm 0x%x", status);
+
+		set &= ~(TIOCM_OUT2 | TIOCM_RTS);
+		clear = ~set;
+		set &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+		       TIOCM_OUT2 | TIOCM_LOOP;
+		clear &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+			 TIOCM_OUT2 | TIOCM_LOOP;
+		status = tty->driver->ops->tiocmset(tty, set, clear);
+		BT_DBG("Clearing RTS: %s", status ? "failed" : "success");
+	} else {
+		/* Set RTS to allow the device to send again */
+		status = tty->driver->ops->tiocmget(tty);
+		BT_DBG("Current tiocm 0x%x", status);
+
+		set |= (TIOCM_OUT2 | TIOCM_RTS);
+		clear = ~set;
+		set &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+		       TIOCM_OUT2 | TIOCM_LOOP;
+		clear &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+			 TIOCM_OUT2 | TIOCM_LOOP;
+		status = tty->driver->ops->tiocmset(tty, set, clear);
+		BT_DBG("Setting RTS: %s", status ? "failed" : "success");
+
+		/* Re-enable hardware flow control */
+		ktermios = tty->termios;
+		ktermios.c_cflag |= CRTSCTS;
+		status = tty_set_termios(tty, &ktermios);
+		BT_DBG("Enabling hardware flow control: %s",
+		       status ? "failed" : "success");
+	}
+}
+
+void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
+			 unsigned int oper_speed)
+{
+	hu->init_speed = init_speed;
+	hu->oper_speed = oper_speed;
+}
+
+void hci_uart_init_tty(struct hci_uart *hu)
+{
+	struct tty_struct *tty = hu->tty;
+	struct ktermios ktermios;
+
+	/* Bring the UART into a known 8 bits no parity hw fc state */
+	ktermios = tty->termios;
+	ktermios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP |
+			      INLCR | IGNCR | ICRNL | IXON);
+	ktermios.c_oflag &= ~OPOST;
+	ktermios.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
+	ktermios.c_cflag &= ~(CSIZE | PARENB);
+	ktermios.c_cflag |= CS8;
+	ktermios.c_cflag |= CRTSCTS;
+
+	/* tty_set_termios() return not checked as it is always 0 */
+	tty_set_termios(tty, &ktermios);
+}
+
 void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
 {
 	struct tty_struct *tty = hu->tty;
@@ -273,13 +352,13 @@ void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
 
 	ktermios = tty->termios;
 	ktermios.c_cflag &= ~CBAUD;
-	ktermios.c_cflag |= BOTHER;
 	tty_termios_encode_baud_rate(&ktermios, speed, speed);
 
 	/* tty_set_termios() return not checked as it is always 0 */
 	tty_set_termios(tty, &ktermios);
 
-	BT_DBG("%s: New tty speed: %d", hu->hdev->name, tty->termios.c_ispeed);
+	BT_DBG("%s: New tty speeds: %d/%d", hu->hdev->name,
+	       tty->termios.c_ispeed, tty->termios.c_ospeed);
 }
 
 static int hci_uart_setup(struct hci_dev *hdev)
@@ -287,15 +366,32 @@ static int hci_uart_setup(struct hci_dev *hdev)
 	struct hci_uart *hu = hci_get_drvdata(hdev);
 	struct hci_rp_read_local_version *ver;
 	struct sk_buff *skb;
+	unsigned int speed;
 	int err;
 
+	/* Init speed if any */
 	if (hu->proto->init_speed)
-		hci_uart_set_baudrate(hu, hu->proto->init_speed);
+		speed = hu->proto->init_speed;
+	else if (hu->init_speed)
+		speed = hu->init_speed;
+	else
+		speed = 0;
+
+	if (speed)
+		hci_uart_set_baudrate(hu, speed);
+
+	/* Operational speed if any */
+	if (hu->proto->oper_speed)
+		speed = hu->proto->oper_speed;
+	else if (hu->oper_speed)
+		speed = hu->oper_speed;
+	else
+		speed = 0;
 
-	if (hu->proto->set_baudrate && hu->proto->oper_speed) {
-		err = hu->proto->set_baudrate(hu, hu->proto->oper_speed);
+	if (hu->proto->set_baudrate && speed) {
+		err = hu->proto->set_baudrate(hu, speed);
 		if (!err)
-			hci_uart_set_baudrate(hu, hu->proto->oper_speed);
+			hci_uart_set_baudrate(hu, speed);
 	}
 
 	if (hu->proto->setup)

drivers/bluetooth/hci_uart.h

@@ -85,6 +85,9 @@ struct hci_uart {
 	struct sk_buff		*tx_skb;
 	unsigned long		tx_state;
 	spinlock_t		rx_lock;
+
+	unsigned int init_speed;
+	unsigned int oper_speed;
 };
 
 /* HCI_UART proto flag bits */
@@ -99,7 +102,11 @@ int hci_uart_register_proto(const struct hci_uart_proto *p);
 int hci_uart_unregister_proto(const struct hci_uart_proto *p);
 int hci_uart_tx_wakeup(struct hci_uart *hu);
 int hci_uart_init_ready(struct hci_uart *hu);
+void hci_uart_init_tty(struct hci_uart *hu);
 void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed);
+void hci_uart_set_flow_control(struct hci_uart *hu, bool enable);
+void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
+			 unsigned int oper_speed);
 
 #ifdef CONFIG_BT_HCIUART_H4
 int h4_init(void);